The primary objective is to use the convolution/superposition method of computing radiation dose to improve the prediction of dose deposition in radiotherapy treatments. This approach is the only one capable of accounting for the dose in situations of electronic disequilibrium encountered near beam and patient boundaries and in regions of tissue heterogeneity. The method will be integrated into an existing treatment planning system to be used as a tool for algorithm research and program development as well as dosimetry research. Further research into the convolution/superposition approach will be undertaken. This includes reducing the calculation time necessary for three-dimensional dose planning, extending its usefulness to electron beam treatment planning and developing it for use in whole body radiotherapy and brachytherapy. Automated optimization is an exciting new area of investigation using deconvolution mathematics. The first aims for optimization will be designing compensation filters and finding the best source positions and activities in brachytherapy. Dosimetry research will be carried out for clinical situations that have electronic disequilibrium and other significant deviations from the geometry of a water phantom. These sites include tumors in the breast, thorax and head and neck. The convolution superposition method will be compared to other dose planning algorithms, measurements and the results of Monte Carlo modelling.